Valve-operating mechanism



March 3, 1931. G. CAVIN I VALVE OPERATING MECHANISM Filed Jan. 18, 19285 Sheets-Sheet 1 l/V I/E IV TOR A TTOR/VEY March 3, 1931. I c v N I1,794,834

VALVE OPERATING' MECHANISM Filed Jan. 18; 1928 5 Sheets-Sheet 2 ATTORNEYMarch 3, 1931. CAVIN 1,794,834

VALVE OPERATING MECHANISM Filed Jan. 18, 1928 5 Sheets-Sheet 5 QJ/a /6@Wk INVENTOB ATTORNEY March-3, 1931. c v 1,794,834

VALVE OPERATI NG MECHANI SM Filed Jan. 18, 1928 5 Shets-Sheet .4

w'zg/ 6M0 IN W? N TOR ATTORNEY G. CAVIN 1,794,834

VALVE OPERATING MECHANISM Filed Jan, 18, 1 928 5 Sheets-Sheet 5 March 3,1931.

. M M W W M M v a m a A mm w 1,. W \V A w n m Patented Mar. 3, 1931GUsrAvEoAvIN, or ritesron, on'ranro, CANADA, ASSIGNOR T AMERICANTHROTTLE COMPANY, Inc, or new Yonminm VALVE-OPERATIN MECHANISMApplication med January is, 1928. Serial in). 247,691.

My invention relates to: valve-operating mechanisms and'has particularreference to devices of the type particularly adapted for use withlocomotive throttle-valves. More specifically the invention relates tothrottleoperating mechanism for. use in con unct1on with throttles ofthe multiple valve type. In

the control oflocomotive throttle valves, it is particularly desirableto provide very accurate control of the'valve when the latter IS in aslightly opened position in order to provide the most accurate controlover the locomotive for spotting and other manoeuvring pur-v poses.There single throttle valves are used,

-' the forces ordinarily. required to operate the throttle are ofconsiderable magnitude, and

accurate regulation ofythe position of the throttle'valve is a seriousproblem. In throttles otthe multiple valve type, thesa'meproblem ispresentand is particularly acute where unbalanced forces are encounteredin the initial opening stages of the valve, due to the use of unbalancedpilot valves which are opened ahead of the main valves. 1 V

In orderto secure the necessary accuracy of control over the throttle, arelatively high leverage ratio must "be employed, but the maximum ratiopermissible is limited by the allowable amount of travel of the throttlelever in the locomotive cab.

In order to secure thenecessary leverage ratio and at the same timelimit the total travel ofthe throttle lever, throttle-operatingbetween'the operating characteristics of different type of throttle, andthepresent invention is in the nature. of an im.-

provement upon the known forms of variable leverage mechanisms;theconstruction of the 1 improved form being such that'the operatingcharacteristics of the mechanism may be'readily adapted to suit thecharacteristics of the individual throttle which it is to operate.

The invention further consists in the novel combinatlons andarrangements of parts which will be clearlyevident from the ensu ingdescription'ot a preferred-form of the invention as applied to amultiple valve throttle. 1

In the accompanying drawings part hereof, Fig; 1 is, aftragmentaryelevation of a locomotive with a portionioi the figiire brolrenawaytoshow theoperating mechag nism'; Fig. 2 lsan elevation onalargersqa l of the mechanism embodying'the, invention;

Fig. .3 l is a diagrammatic ,section'; taken} through the longitudinalcenterlineof thej mechanism shownin Fig. Q'andfshoWingft;

spectively in full and dotted .lines;,the p(jsition otthe operatingleverin. closed ia'ndop'en:

position; Fig. 4 is a section taken transversely through the operating.mechanism, Fig.

Fig; 6 isa transverseelevation partly in sec;

illustrated'inthe preceding figures).

Referring now toFig. 1 ,:thefl @emotiv is shown equipped withaso-calledffoutside throttle locatedinithe smoke-box 1 andjop; erated from-theexterioriof the smoke-box by means of a cam shaft2 extending through v aa5 a section taken ontheline. 5 5 of Fig. l;

a suitable stuffing box 3 bThej shaftcznisfi provided on itsouter endwith an operating crank 4, to which is. pivoted:.the thrOttlQIQdf 5extending along the locomotive vtothe flab; where it is attached to theoperating mecha'{ nism indicated generally at 6.

The throttle isopened and closed bylongi tudinal movement of the rod 5and this mo-] tion is manually controlled through d the medium of theoperating mechanism. shown in detail in Figures 2 to.5. ,7 Referring nowto these figures,the operat ing mechanism comprises. a bracket Z adapted to be secured to the rear head'of the locomotive, and to whichissecured the {casting 8, the latter comprising aflatplatefportion 9 anda hollowcylindrical portion 10 having a bore inwalinementwith the rod 5.

The rod 5 is securedto a cylindrical sliding member.- 11 having aworking fit L within the cylinder 10 and provided. intermediate its endswithv a vertical, slot 12. The; forward.

and rear ends of slot .12 are preferably .defined by. separable bearing.members 1 3 and 14 suitably secured to the member 11, as by rivets 15.Ihe member 13, as will be seen from Fig. 3, is formed with a planevertical forward face 16 extending a short distance below the bottom ofmember 11, and the forward member 14 is carried a greater distance belowmember 11 and terminates in a rounded rearwardly projecting bearing face17.

The cylinder 10 is provided with a slot 18 above slot 12 and acorresponding slot 19 below slot 12. The flat face portion 9 of thecasting 8 is drilled above the slot 18 about midway of its length toaccommodate a pivot 20, the latter sup orting a throttle lever 21 whichextends ownwardly through the alined slots 18, 12 and 19 and terminatesat its lower end in an operating handle 22.

The portion of the throttle lever 21 passing through the slots in thecylinder 10 and member 11 isenlarged to form a rearwardly projecting camsurface 23 and a forwardly projecting surface 24, the former of saidsurfaces being struck on a long radius, the chord of the are lying ataslight angle to the longitudinal axis of the lever. The upper portionof the forward cam face 24 extends downwardly and diagonally away fromthe longitudinal axis of the lever along a substantially straight line,while the lower por-- tion of the cam is substantially arcuate in form,extendingback toward the longitudinal axis of the lever. V I

Referring now to the full line position shown in Fig. 3, it will be seenthat the cam surfaces 23 and 24 of the throttle lever are soproportioned that when in the closed position the rear cam face 23contacts with the member 13 at the upper end of the face 16 while theforward cam face 24 makes contacts with the rearwardly projecting face17 of the member 14. From this arrange ment it will be evident that whenthe lever 21 is in this position the member 11 is held -through thecylinder 10, thereby imparting motion to the rod 5 and through the lever4 and shaft 2 actuating the throttle valve to open it. i

As the lever 21 is moved progressively to open position, the point ofcontact between the cam face 23 and the face 16 moves progressivelydownward until it reaches the lower edge of the face 16 as is shown inthe dotted line position in Fig. 3. Obviously this movement of the pointof contact between these members provides a gradually decreasingleverage applied'to the member 11, so that when the latter is in itsforward or closed position the maximum leverage may be applied thereon,and as it is moved to its rearward or open position the leverage isprogressively decreased and the relative amount of movement of member 11for a given movement of lever 21 progressively increased.

- The casting 8 is provided with lugs 25 to In order to provide areadily releasablii;

latch for holding the throttle in a proper par-- tially opened ordrifting position, the slotted lug 30 is secured to the side of mem ber26 by means of studs 31. The lower face of the lug 30 is formed withbeveled ends 32 and a centrally located notch 33. Mounted on thethrottle lever is the plunger 34 movable vertically in a suitable block35 and urged to an upper "position by spring 36. The maximum upwardtravel of plunger 34 is limited by the shoulder 37 formed in themounting block 36, and this position is such that when moved past thelug 30 the plunger 34 will engage the beveled faces 32 of the lug. Asthe lever is pushed past the lug 33 in either direction, the plunger 34is the-- pressed until it strikes the notch 33, forming a stop which,however, may be readily released by direct force applied to the leverhandle 22. The notch 33 is used only to indicate the proper driftingposition of the lever 21 and is not relied upon to hold the lever inthis position, as the lever is secured in any given position by meansofthe pawl 23.

As the characteristics of individual loco motives vary, even though theymay be of the same design, and the lug 30 is made adjustable, so that byloosening the studs 31 lug 30 may be moved longitudinally to a positionsuch that the stop recess 33 will indicate the proper drifting positionfor that particular locomotive and the lug 30 may be then permanentlysecured in place by tightening the studs.

Referring now to Fig. 6, a known form of multiple throttle valve isshown comprising a bi-chambered casing 38 provided with a plurality ofalined ports 39 affording communication between the inlet chamber 40 andoutlet chamber 41. Each port is controlled by means of a main valve 42and each of these valves is in turn provided with a small pilot valve43, the latter valves acting to balance the main valves before thelatter are opened. Both the main valves and the pilot valves areactuated by the cam-shaft 2, the latter being provided wit-h suitablecams 44. In the particular form of throttle shown,the

before the first main valve is lifted from its balanced'pilot valveshave all been opened and there remains to be opened only the main valveswhich have been balanced by the opening of the pilotvalves.

In the form of mechanism illustrated, this characteristic is provided aswill be apparent from Fig. 7. Referring now to this figure, it will beseen that the first six inches of travel of the throttle handle resultsin a movement of the throttle rod 5 by less than one inch so that theleverage ratio through this range of movement of the mechanism isgreater than 6 to'l. The cam arrangement in the throttle. valve is suchthat during this initial opening range Where the high leverage ratio isavailable, the pilot valves are all ened. Upon continued openingmovement of the throttle, the leverage ratio decreases as will be seenby reference to the relative travels of the throttle handle and thethrottle rod when the former is moved; from, for example, 10 told inchesfrom the closed position. During this .four inch travel of the throttlehandle, the throttle rod moves con siderably more than one inch so thatthe leverage ratio is reduced to less than 4 to 1.

It will be readily apparent that the leverage ratio secured may bewidely varied by suitable variation in the contour of the cam face '23of the throttle lever and its relative position with respect to thepivot 20. The form of this cam face willdetermine the relative travel ofthe throttle lever and the throttle rod, and once the proper contour forthe desired leverage ratios isdetermined, the con tour of the cam face24 may be readily determined, this cam face being arranged so thatthroughout the operating range of the throttle lever the bearing face 17on member 141: makes contact with the forward cam face. Thedetermination of the proper contour of cam face 24 is necessary only toeliminate lost motion, as the relative motion of the throttle rod 5 withrespect to the throttle lever 21 is the same in either opening orclosing movement. I

The invention is obviously subject to various changes and modificationsin the specific form of apparatus by which it may be carried intoeffect, and the embodiment herein shown is therefore to be taken asillustrative only and not limiting in sense.

I claim:

1 In apparatus of the class described, the combination with a leverhaving a fixed piv- 0t and provided with a cam face, of a longiweieal yl dea da t d t et ma passing member having a portion emb r;sa -memb ibeism ante 'zw 7 i. an e wsena e rii e P i f e lever:

math li "arenas-a l y sad-Gamma trespass snare e'that is die aaaa i' tofc npaabaw ea the fleyeri it rve la euta e pt ot, a v ve. d m a Ineeetiii he l di g member with the] valve to actuate the latter. i r

2, In apparatus oflthe class described, the l fabif long uclinal ly-;slidingf member, having a rel ti ely-.- ed; ce d p l o; r l g b v aidfae germ m ei ai m m er; a l e aaclm ms enm t 'ngs'ai l e with i memb n faid mem er? eing nt d th repeat; to, said lever so that] the distancetween r hapivet po n e lever Y nd the point of, contact. between I thelever and the 91 with new n -e fi eel ivvt; ded,with a convex cam face,o f a sli ling member increases as thef lever moved about its pivot to,openthe valve,

' 3.; A; throttle actuating, neshanism mpri n -a at- 1 51 s et, ene'tadiae ly. li ing Y a iI1gafi d p vbtl n, sa dblra fiand 1 adap ed. ij aua' aid mem aid; is? 1v ra k tb lls-inten ed v tllpeene r' d 1 -1 a a.at-inacam a ea heloe twn a d con ur??? aidi facesl' eiegfit hthat thevemeeratioi em er arr ed y Said, h ek t;

between said 'lQ IQI', andsaid member variies as theilevefr,1smweataitiispivat Ameanat ains: ne ai m com-f prising' a mounting aoket, aslotted'j longiudi allyr idi ack t, a. ev r Havi fixed a pivot on saidmembef earned by i d r ttleness 'idinal rani rse y h u of leverbeingiprovidedwithcurved can; faces of; different contour engaging?cooperat-ing faces onsaid;member in line contact to mac hela te einv s531A throttle, actuating mechanism comprisinga inountingbracket, aslotted longitudinallysliding me her carried by said brack et, aljeverjhaving a: fitted? pivot on saiarbmckthrough said slot, said lever beingprovided with curved cam surfaces on opposite sides thereof, one of saidsurfaces engaging a cooperating surface at one end of the slot to movesaid member as said lever is movedin one direction about its pivot, theother of said surfaces engaging a cooperating surface at the other endof saidslot to move said member in the opposite direction as the leveris moved about its pivot in the opposite direction, and the contour ofsaid cam surfaces being such that there is substantially no lost motionbetween the lever and the sliding member in any operative position ofthe lever.

6. A throttle actuating mechanism comprising amounting bracket, a valveactuatlever is "about g sa d member, the opposite sides ing membersliding longitudinally therein and provided with an operating face, andan actuating lever having a relatively fixed pivot at one end and alateral cam face arranged to engage said first named face in rollingcontact as the lever is moved about its pivot, whereby the distancebetween the point of contact between said faces and the fixed pivotvaries as the lever is moved about its pivot.

7. In apparatus of the class described, the combination ofa'longitudinally sliding valve operating member having spaced op- Vposed transverse bearing surfaces, a lever having a fixed pivot at oneend and passing between said surfaces, said lever being provided withcurved cam faces each engaging one of said surfaces in line contact,said lever being so arrangedwith respect'to said member that thedistance between the pivot and the lines of contact between the leverand the sliding member varies as the lever is moved about its pivot.

8. In apparatus of the class described, the

combination of a slotted longitudinally sliding valve operating memberhaving aplane bearing surface at one end of the slot, a lever having afixed pivot at one end and passing through said slot, said lever beingprovided with a convex cam face engaging said plane surface in linecontact, and said lever and said member being arranged so that theposition of the lineof contact between the cam face and the bearingsurface changes as the lever is moved about its pivot.

9. In apparatus of the class described, the combination of a slottedlongitudinally sliding valve operating member having a plane 7 bearingsurface at one end of the slot and an opposed. convex bearing surface,at the other end of the slot, said last named surface beingsubstantially offset with respect to the axis of said member, a leverhaving a fixed pivot and passing through'said slot, said lever havingopposed convex cam faces engaging said surfaces in line contact to movesaid member asthe lever 1s moved about 1ts, plvot.

GUSTAVE GAVIN.

